The conviction rate for rape is 58%. That bears repeating. The conviction rate for rape, is 58%. The conviction rate for reportable crimes of all types is 57%. I know you will have heard the figure of 6%. Everyone has. That figure is actually an attrition rate, not a conviction rate, and even as an attrition rate it is wrong – the attrition rate for rape is in the region of 12%.

An attrition rate is the amount of convictions resulting from reports of a crime, and is not routinely calculated for any crime other than rape. Therefore without manually undertaking the exercise, it is impossible to compare the (true) attrition figure for rape with other crimes. A conviction rate is the amount of convictions following a trial, and is calculated for all reportable crimes.

Why is this important? Because the rhetoric of rape, which largely propounds myths, puts survivors off reporting the crimes committed against them, making them perceive that the system designed to assist them is actually wholly against them.

Last week, Mumsnet released a survey of its users as part of its We Believe You rape awareness campaign. Sixty-eight per cent of respondents said low conviction rates would make them hesitate to report a rape due to low conviction rates – clearly they had heard the 6% figure too.

It isn't just conviction and attrition rates that are an issue and which impact on rape reporting. The whole discourse about rape is mired in myths and half-truths, which leads survivors to believe the system is against them and that they are unlikely to be believed.

Last week, the court of appeal heard the appeal against conviction in what has become known as Sarah's case. In 2010, 'Sarah' reported that her husband had raped her. After the prosecution had started, she retracted that allegation; then subsequently withdrew the retraction. Sarah was convicted of perverting the course of justice, and sentenced to eight months in prison.

In respect of the sentence the court of appeal moved quickly, and Sarah had her sentence reduced to a community sentence after she had served three weeks in prison. The director of public prosecutions, Keir Starmer, made it clear he was appalled Sarah had been prosecuted, and swiftly changed the guidance so that in future prosecutions can only be brought in such cases with his permission.

Sadly, the way Sarah's case was commonly reported last week can only be described in some instances as hysterical. There were the expected headlines of "rape victim sent to prison for withdrawing allegation" with little explanation that such a thing is highly unlikely to happen again, owing to the change in guidance, and that the court of appeal had very quickly ordered Sarah's release.

I asked Vera Baird, the former solicitor general and one of the commentators on Sarah's case, to make it clear that we were unlikely to see this situation repeated because of the change in guidelines, in order to ensure survivors would not fear that what happened to Sarah would happen to them. Sadly, she responded that I was "optimistic" and that the police would simply use the charge of wasting police time in order to get around the guidelines, and that the Crown Prosecution Service would not change the guidelines for that offence to match the change made to perverting the course of justice. As the law stands, the guidelines on wasting police time are the same as perverting the course of justice, in that prosecutions require the consent of the DPP – it is unfortunate the former solicitor general did not seem to know this.

What I would like to see is openness about rape. The myths, the half-truths, and the nowhere near the truths do not help survivors come forward, never mind helping them come forward with any confidence. I would like to see the full picture being presented. I accept there is still huge scope for improvement in the criminal justice system in the way victims are treated. But change has happened, and will continue to happen, and we need to get that message out there, too.